Suzanne Moore is assuring me earnestly that she is not, and never has been, a hardened drug addict. We are sitting in her kitchen, past the bright pink glare of her living room, the skewwhiff numbers on her front door, and the outer walls that are painted in wild, clashing pastels. Her middle daughter, Bliss, 19, has just wandered in and out in search of toast, and on hearing that this is an interview, has said that all she really knows about her mother's life is she was "a junkie for about 10 years". Moore laughs at this. We all laugh. And then, as Bliss leaves the room, Moore sighs. "I really need a spin doctor, don't I?"

It is certainly hard to see Steve Hilton or Alastair Campbell putting up with this kind of teenage joke (and yes, it is a joke), however well delivered. But then this small corner of the general election campaign is not quite politics-as-usual. Moore has always been a one-off. She is a leftwing journalist who moved from Marxism Today to the Mail on Sunday; a feminist once lambasted by Germaine Greer for her big hair and "fuck-me shoes"; a single mother who has had three daughters, with three different men, in three different decades.

Now she is standing as an independent candidate in the Hackney North and Stoke Newington constituency she has lived in for just under 20 years, a decision she announced a few weeks ago in her regular MoS column. Moore was disillusioned with the current political system – like many, she disagreed with the Iraq war from the start, was demoralised by the expenses scandal, and depressed by the dearth of choices on offer – and wanted to engage with democracy through "DIY politics". "Is it possible to be yourself and stand for election?" she wrote. "I shall find out."

Hackney North and Stoke Newington is an "ultra-safe" Labour seat, with a 7,500 majority, in which, according to an analysis of voters' power, each person's ballot is worth 0.067 of a vote. "I thought, I'm not empowered as a voter – could I be empowered as a candidate?" she says. Is she worried about being pigeonholed with that other high-profile independent candidate, Esther Rantzen? "What category is that? Mad old woman?" No, attention-seeking. "Well," she says, "the reaction is fairly split between people who think you're just a mad, attention-seeking nutcase, and the people who come up and say 'go for it'. But for me, this is a look at whether democracy works, almost going back to my old leftie and sometimes anarchist politics, and saying, 'I'm just gonna do it.' . . . The system says 'you can do it', but can you really?"

Her decision is, on some level, controversial – she's contesting the seat of Diane Abbott, who made history in 1987 by becoming the country's first black female MP. (Shamefully, there's still only one other black woman in the Commons: fellow Labour MP, Dawn Butler.) Moore has been complimentary about Abbott in the past – praising her advocacy for young black men, for instance – but was incensed by her decision to send her son to private school, a move that Abbott herself described as "indefensible".

She must have thought twice about challenging such an important figure? Moore agrees that Abbott's initial win was hugely significant, but says that there is a feeling, locally, "that [Abbot's] not here enough, she's been around too long, she's too tied to Westminster". What would Moore say to the argument that, on principle, it's wrong to stand against one of the only two black women in the Commons? "I'd say that's pretty racist actually . . . I don't think that there should be anyone in power who's considered unassailable, whether they're a man, woman, black, white."

I ask Moore whether she might get in, and she has no illusions: "There's the political answer, and there's the reality, that this is a safe Labour seat." But there's no doubt that if she did win, unlikely as that is, she'd shake up the establishment.

Moore was born in 1958, in Ipswich, to a mother who was a working-class Tory and an American father – her parents split up when she was a small child. The yearning to escape started early. She once wrote that, growing up, all she had ever wanted to do was leave her home town. Did she find it boring? "Yeah, totally conformist." She attended an all-girls' grammar. "Absolutely the kind of school that everyone wants their children to go to now, but horrible, awful. Living hell. Totally uniform."

She became a "very, very rebellious teenager, in every possible way . . . I was good at school until I was about 14, then hormones kicked in." At 16, she decided to leave school, prompting a confused conversation with her headmistress. She was told they had been lining her up to go to Cambridge, to which she replied she had already been; she had recently attended a gig there. It only dawned on her later that this was a reference to the university, because "no one had spoken to me about that stuff. If you're not brought up in a certain way, these things aren't available to you, and you don't even know what they mean." The head- mistress asked what she was going to do next. "I said, 'I could be an astronaut, or I could be prime minister!' Completely insane. Of course I couldn't have been an astronaut – I don't even like flying."

She moved into a bedsit at 17, and spent the next seven years working and travelling, flitting between jobs and countries. "I sold encyclopaedias in New Orleans, I was a social worker in Haringey. I've been a waitress, I've worked in shops. I've been an audiology technician, learning how to do hearing tests. I went around South America, India, and then, in New York, I decided to be a psychoanalyst." She returned to Britain, embarked on a psychology degree at Middlesex University and "hated it. Psychology just seemed to be a lot of tests, experiments to show that women couldn't drive, that sort of thing", so she switched to cultural studies. "Marxism, post-structuralism – they made me question the other stuff I was being taught." As a leftwing student, she was involved in protests, marches and other direct action. "People remember the 80s for its style, and for yuppies, but they forget that it was a real decade of dissent: the miners' strike, Greenham Common."

After receiving a first for her BA, she started a PhD at Middlesex, on Theories of Pleasure, and also began writing her first pieces of journalism. "I thought you could do both, but people very quickly said, no, you've got to choose." She quit the PhD after 18 months. "I got frustrated with the idea that you would do all this work, and three people in the world were going to read it." Instead, she landed a job editing the cultural pages of Marxism Today, before becoming a film critic for the New Statesman.

Moore had her first child, Scarlet, when she was at university in her mid-20s; she had Bliss in her early 30s; 10 years later, she had another daughter, Angel. She has been a single mother pretty much throughout. Given her experience of having a child in three separate decades, she says she "probably" agrees with Hilary Mantel's recent comments that women might sometimes benefit from having children when they're young. "When I had Scarlet, I had no money but a lot of energy, and as you get older, you have – well, luckily for me – more money, but less energy. I've known so many people who have left it, and left it, and then had problems. You just want everyone to be aware of the choices they have to make."

She has always had a feminist outlook, she says, formed partly as a result of seeing her mother, who was "in lots of ways really strong, but trapped by her relationships with men. Financially dependent. I think I decided very young that I would never be financially dependent on a guy." It is a decision she has stuck to. But Moore didn't always call herself a feminist; at first she was "loth to identify with it, because while I thought that, as a woman, I could do whatever I liked, I also thought, 'Yeah, but I do like lipstick.'" After realising the two interests were compatible, she became one of the most popular feminist writers in the country.

Given her leftwing politics, feminism and sometime anarchism, it was a surprise when Moore became a columnist for the Mail on Sunday, following stints at the Guardian and Independent. Plenty of journalists have drifted from left to right, but this isn't the case for her: the political slant of her opinions hasn't changed. Was it a difficult decision to move to such a rightwing paper? "I did have to think about it," she says, "but my stance has always been to make ideas popular, to talk to people who are different from you. I've always been completely straight about the fact that there were two reasons why I went. One was the money, and one was the idea of having such an enormous readership, where I wouldn't be preaching to the converted."

She was also attracted to the idea that it was a readership that could decide an election, and having spent years communicating political ideas on paper, she is now doing the same on the streets of her constituency. Her local proposals include filling the many hundreds of empty council properties, reviving the Stoke Newington festival, and setting up micro-financing schemes for small businesses. And having been despondent about the national choices on offer at the start of the election campaign, she wrote excitedly about the rise of "Cleggbama" in her last column: "I am not a Lib Dem but I share absolutely a sense that something has to shift and am excited to think it might."

She would particularly like to see more honesty in politics; candidates who are recognisably human, not required to have 2.4 children, a devoted spouse, and a spotless past. "We now have a situation where we know that people have taken drugs, but they have to say 'I didn't like it'. I'm not a junkie, like Bliss said, but I can say that I've taken drugs and liked it. I can't pretend otherwise. The fact is that, now, if you're of a certain generation and you haven't slept around, taken drugs, you're just not normal, so what are we going to do? . . . Do you want the people who represent you to be flawed, or to embody this perfect ideal? Because we've had the perfect ideal, and that's given us the bloody expenses scandal and two wars."

Not everyone's impressed by the honest approach. Out canvassing recently, a man looked askance at her campaign material. "Christ," he said, "I might be disillusioned, but it'll be a long time before I vote for an anarchist." Moore laughs at the memory, quite unperturbed.